What is breast cancer?

Breast cancer is when cells in your breast grow in an uncontrolled way and form a tumour. It is the most common cancer in the UK. Breast cancer mainly affects women but men can also get it, although this is rare. We don’t know what causes breast cancer. But we do know that it is influenced by your age, lifestyle and family history. There are different signs and symptoms of breast cancer, including:

  • a lump in the breast
  • a change in the size or shape of the breast
  • dimpling of the skin or thickening in the breast tissue
  • a nipple that’s turned in (inverted)
  • a rash on, or discharge from the nipple
  • swelling or a lump in the armpit.

If you are worried about your breasts, you should see your GP. Most breast lumps are not cancer but they should always be checked out. The most common treatments for breast cancer are surgery, chemotherapy, radiotherapy and hormonal therapy. Improvements in treatments mean that more people are being cured or are living for longer.

What is cancer?

The body is made up of tiny building blocks called cells. Usually, these cells divide to make new cells in a controlled way. Sometimes, this goes wrong and the cell becomes abnormal.

The abnormal cell keeps dividing and making more and more abnormal cells. These cells form a lump, which is called a tumour. Not all lumps are cancerous. Cancer cells sometimes break away from the primary cancer and travel through the blood or lymphatic system to other parts of the body. Cancer cells that spread and develop into a tumour somewhere else in the body are called a secondary cancer.

Living with breast cancer

Karen talks about her experience of living with breast cancer and how it affected her finances.

About our cancer information videos

Living with breast cancer

Karen talks about her experience of living with breast cancer and how it affected her finances.

About our cancer information videos


The breasts

Breasts are made up of fat, supportive (connective) tissue and glandular tissue containing lobes. In women, the lobes (milk glands) are where breast milk is made. They connect to the nipple by a network of fine tubes called ducts. Men have a small amount of breast tissue behind the nipple.

Female breast
Female breast

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Causes and risk factors

We don’t know what causes breast cancer. There are some risk factors that can increase your chances of getting it.

For women, these include:

  • Age – The risk of developing breast cancer increases with age.
  • If you have had cancer or other breast conditions before.
  • Hormonal factors – Exposure to the hormones oestrogen and progesterone for long periods can affect your breast cancer risk.
  • Lifestyle factors – Drinking alcohol increases your risk of developing breast cancer, but the increased risk is small for women who drink within the recommended guidelines. Being overweight, particularly over the menopause, and smoking heavily also increases your risk.
  • Family history – Only 5–10% of breast cancers are thought to be caused by an inherited breast cancer gene. Talk to your doctor if you are worried about your family history.

Some risk factors for men are different.


Symptoms of breast cancer

These include:

  • a lump in the breast
  • a change in the size or shape of the breast
  • dimpling of the skin or thickening in the breast tissue
  • a nipple that’s turned in (inverted)
  • a rash (like eczema) on the nipple
  • discharge from the nipple
  • swelling or a lump in the armpit.

In both women and men, the most common symptom of breast cancer is a lump in the breast.

If you have any of these symptoms or any that aren’t mentioned here, get them checked by your GP.


Diagnosing breast cancer

You should see your GP if you have any symptoms or worries about your breasts. They will examine you and, if necessary, refer you to a breast clinic to see a specialist doctor or nurse. Some women are referred through the breast screening programme. At the clinic, you will see a breast specialist. They will ask if you have had any breast problems before and whether you have a family history of cancer. The specialist will examine your breasts and under your arms. They will explain which tests you need. These may include:

  • mammogram
  • breast ultrasound
  • ultrasound of the lymph nodes in the armpit
  • biopsy.

If these tests show that you do have breast cancer, you may have other tests to prepare for an operation or to find out more about the cancer. These include:

  • blood tests
  • a chest x-ray
  • an MRI scan
  • a CT scan.

Waiting for test results can be an anxious time. It may help to talk about your worries with a relative or friend. You could also speak to one of our cancer support specialists.


Types of breast cancer

There are different types of breast cancer. Knowing the type allows your doctor to plan your individual treatment. Most breast cancers are invasive. This means the cancer cells have spread outside the lining of the ducts or lobules into surrounding breast tissue. There are several other types of breast cancer, but they are treated in similar ways.

We have more information about the different types of breast cancer in women and men.


Staging and grading of breast cancer

When breast cancer is diagnosed, it’s important to know the stage and grade of the cancer so that the best treatment can be planned. The stage describes the size of the tumour and whether it has spread. The grade tells you how quickly it might grow.

Staging

The most common systems to describe the stage of a cancer are the TNM staging system and the number staging system:

  • TNM staging looks at the size of the tumour, whether the cancer has spread to the lymph nodes and whether it has spread to other parts of the body.
  • Number staging describes breast cancer in four stages. From stage 1 (very small and hasn’t spread to the lymph nodes in the armpit) through to stage 4 (the cancer has spread to other parts of the body).

Grading

Grading shows how the cancer cells look under the microscope compared with normal breast cells.

  • Grade 1 (low-grade) – The cancer cells look similar to normal cells and grow slowly.
  • Grade 2 (moderate-grade) – The cancer cells look more abnormal and are slightly faster growing.
  • Grade 3 (high-grade) – The cancer cells look very different from normal cells and tend to grow quicker than grades 1 and 2.


Hormone receptors

Hormones exist naturally in the body. They help to control how cells grow and what they do in the body. Some breast cancer cells have receptors which allow the hormones oestrogen and progesterone to attach to the cancer cell. If there are a large number of oestrogen receptors, it is known as oestrogen-receptor positive or ER-positive breast cancer. If not, it’s known as oestrogen-receptor negative or ER-negative breast cancer. Many ER-positive breast cancers respond well to hormonal treatments.


Treating breast cancer

For most people, the first treatment for breast cancer is surgery to remove it. You will usually have additional treatments to reduce the risk of the cancer coming back. These treatments may include:

Your doctor and breast care nurse will explain the treatments they think are best for you.

They will ask about your preferences, explain the options available and can help you if you need to make decisions about treatment.

Research into breast cancer is going on all the time. Better treatments mean more people are cured or living for longer. Your breast specialist may ask you if you would like to take part in a clinical trial. You can read more about this in our information about clinical trials.


After treatment for breast cancer

You will have regular check-ups after treatment. These will include a physical examination and mammograms. Many people get anxious before check-ups. This is natural. You may find it helpful to talk to family and friends. You can also contact the Macmillan Support Line.

Your nurse will explain what to look out for in your treated area. Contact your specialist or nurse if you notice anything unusual between your appointments.

Side effects

Some treatments may cause side effects, such as lymphoedema or infertility. You can speak to your nurse about this. You may be able to store eggs or sperm before you start treatment. We have more information about fertility in women and fertility in men.

Maintaining a healthy lifestyle

You might want to make positive lifestyle changes after treatment. For example, by being more physically active, eating healthily, or stopping smoking. Some breast cancer treatments can cause bone thinning or heart problems later in life. Making changes to your lifestyle can help to keep your bones or heart healthy.

Physical activity after breast cancer treatment

Joy explains how she followed exercises that were tailored to her cancer type and gradually became more active after breast cancer treatment to help with her recovery.

About our cancer information videos

Physical activity after breast cancer treatment

Joy explains how she followed exercises that were tailored to her cancer type and gradually became more active after breast cancer treatment to help with her recovery.

About our cancer information videos


More information about breast cancer

This page is a short summary of our information about breast cancer. We have more detailed information about breast cancer in women and breast cancer in men. Our cancer support specialists can also give you general support and answer any questions you may have. You can speak to them for free, Monday–Friday, 9am–8pm, on 0808 808 00 00.

Back to Breast cancer

Diagnosing

causes and risk factors of breast cancer

Organising

the practical, work and financial side

Treating

breast cancer and what to expect

Coping

with and after breast cancer treatment

Resources

and publications to order, download and print